Analysis of calcaneonavicular coalitions using multi-planar three-dimensional computed tomography

Abstract

Purpose Computed tomography (CT) is the current imaging standard for confirming the diagnosis of a calcaneonavicular coalition. The purpose of this study was to evaluate three-dimensional (3D) multi-planar CT images of calcaneonavicular coalitions and adjacent tarsal relationships, compared to controls, in order to obtain an understanding of the 3D anatomy for classification and as an aid to surgical resection. Methods All patients who underwent CT of bilateral feet at our institution to evaluate a suspected calcaneonavicular coalition between 9/2005 and 3/2008 were retrospectively reviewed. Seventy-four feet (37 patients) were included in this analysis. In addition, 12 patients with a presumed normal calcaneonavicular relationship, who underwent CT of bilateral feet for various other diagnoses, were included as a control cohort. Seven measurements were performed on the 3D reconstructions to quantify the shape of the coalition (dorsal and plantar widths of the calcaneal and navicular contributions, coalition depth of the calcaneal and navicular contributions, and coalition length). The coalitions were classified into four types based on their appearance and their relationship to adjacent tarsal bones. Results 32/37 patients (86%) were noted to have bilateral involvement (69 coalitions). Coalitions were categorized into four types: Type I (forme fruste)-28%, Type II (fibrous)-23%, Type III (cartilaginous)-45% and Type IV (osseous)-4%. The average shape of the coalition was found to be a curved wedge, which was on average 16 mm wide dorsally, 7 mm wide on the plantar surface, 10 mm in length, and 25 mm in depth. Conclusions 3D CT reconstructions enabled the classification of the spectrum of calcaneonavicular coalitions. The shape of the cuboid was found to correlate with the extent of ossification. In Type I or II coalitions, the cuboid extended medially plantar to the fibrous connection. In more complete Type III or IV coalitions, the cuboid was ''squared off'' and remained lateral to the osseous bridge. An understanding of the 3D anatomy is important when diagnosing milder forms of coalitions, and during resection in order to avoid iatrogenic injury to the calcaneus, head of the talus, or cuboid.

Análisis tomográfico de la alineación del retropié en pacientes con coaliciones tarsianas

“…No se encontraron diferencias estadísticamente significativas en la distribución por edad y sexo (p = 0,3630 y 0,2415, respectivamente) (Tabla 1). De acuerdo con la clasificación de Upasani y cols., 11 las CCE tuvieron la siguiente distribución: frustra (n = 5, 16%), fibrosa (n = 5, 16%), cartilaginosa (n = 17, 55%) y ósea (n = 4, 13%). Según la clasificación de Rozansky y cols., 12 las CAC se presentaron como tipo I: lineales (n = 8, 32%), tipo II: lineal con gancho posterior (n = 2, 8%), tipo III: teja (n = 4, 16%), tipo IV: ósea (n = 9, 36%) y tipo V: posterior (n = 2, 8%).…”

“…Las CCE fueron clasificadas de acuerdo con Upasani y cols. 11 en cuatro tipos: frustra, fibrosa, cartilaginosa, ósea. En la CAC, utilizamos la clasificación tomográfica basada en la reconstrucción 3D propuesta por Rozansky y cols.…”

Signo radiológico: "Nariz del oso hormiguero"

“…Por estas razones, en la mayoría de los casos el estudio radiológico se debe complementar con TC o RM que son herramientas valiosas en la evaluación de las coaliciones tarsales (3) . Estas modalidades, además de evidenciar el signo del oso hormiguero (Figuras 4 y 5), también permiten diferenciar las coaliciones óseas de las no óseas, determinar la presencia de edema de médula ósea, extensión del compromiso articular y cambios degenerativos que afecten las articulaciones adyacentes, esto último muy importante para elegir el procedimiento terapéutico más adecuado (7,9) .…”

Stress Fracture of the Anterior Process of the Calcaneus

“…An osseous calcaneonavicular coalition is most often diagnosed using conventional 45° medial oblique radiographs of the foot or axial plane CT. 7,9 However, a nonosseous calcaneonavicular coalition can be more difficult to detect on plain radiographs. Upasani et al 8 described the usefulness of multiplanar 3-dimensional CT for diagnosing nonosseous calcaneonavicular coalition and revealed that the characteristic features of nonosseous calcaneonavicular coalition include cortical irregularities at the tip of the calcaneus, an ossicle, further blunting of the cuboid extension, narrowing of the nonossified gap between the calcaneus and navicular bones, and/or a distinct squaring-off of the cuboid bone as observed on CT. Using these radiographic methods, the stress fracture in our patient was categorized as a normal type (no calcaneonavicular coalition; Figures 1 and 2).…”

“…In addition, there was no finding to suggest calcaneonavicular coalition, such as an osseous coalition, an ossicle between the calcaneus and navicular bone, or a cortical irregularity. 7,8 Meanwhile, a long anterior process of the calcaneus was observed on CT. Stress fracture of the anterior process of the calcaneus was diagnosed on the basis of radiographic and clinical findings.…”